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Background: Chihuahua represents an increasingly widespread breed predisposed to cardiac disease. N-terminal pro-B-type natriuretic peptide (NT-proBNP) might be a useful point-of-care biomarker for dogs suspected of having heart disease, but breed differences have been reported. The urinary aldosterone-to-creatinine ratio (UAldo: C) appears to be a good indicator of renin-angiotensin-aldosterone system activity in dogs, but Chihuahuas showed significantly higher UAldo: C than other breeds. The objective of this study was to assess preliminary breed-specific reference intervals for NT-proBNP and UAldo: C in healthy Chihuahuas and evaluate sex differences in these parameters. Results: Forty-three healthy Chihuahuas dogs were enrolled. The median NT-proBNP was 347 (125–515) pmol/L, and the median UAldo: C was 2.59 (1.57–4.61) µg/g. The NT-proBNP reference interval was 125 (90% CI 125–125) – 2121.4 (90% CI 941.6–2248) pmol/L. 91% of the Chihuahuas were below the nonbreed-specific cut-off (900 pmol/L). The UAldo: C reference interval was 0.6 (90% CI 0.5–0.9) – 16.8 (90% CI 10.9–27.4) µg/g. No significant sex differences in NT-proBNP or UAldo: C were found. Conclusions: The median value, interindividual coefficient of variation and reference interval of NT-proBNP were in line with those reported for other small breeds. In contrast to previous studies, no sex differences in NT-proBNP were detected. As previously suggested, Chihuahuas seem to be characterized by higher values of UAldo: C than other breeds. [ABSTRACT FROM AUTHOR]

The incidence of dystocia in companion animals is relatively low compared to other farm animals, however when dystocia occurs it needs immediate intervention. The present report is a case about successful management of caesarean section in a Chihuahua dog that suffered from dystocia due to fetal hydrocephalus. [ABSTRACT FROM AUTHOR]

A 2‐year‐old chihuahua dog exhibited recurrent mounting episodes toward both known and unknown individuals. The findings from both the physical and blood tests were unremarkable. After ruling out other physical and psychological diseases, displacement behaviour was suspected. Occurrences of mounting behaviour might sometimes be due to conditions unrelated to reproduction. As such, neutering is only advised after a precise diagnosis, and would not have been helpful in this particular situation. Chewing was used as a major activity alternative to provide the dog with an adequate behavioural activity. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Veterinary Journal / Revue Vétérinaire Canadienne is the property of Canadian Veterinary Medical Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This document is a collection of abstracts from the 11th Asian Veterinary Ophthalmology Annual Conference held in Taipei City, Taiwan in October 2023. The abstracts cover various topics related to veterinary ophthalmology, including case reports and research studies. Some of the topics discussed include the use of modified rhytidectomy for entropion in Shar Pei dogs, the use of hyaluronic acid injection for entropion treatment, the effects of intracameral tissue plasminogen activator injection on intraocular pressure control after cataract surgery, the application of corneal bandage lens for deep corneal ulceration treatment in cats, and the evaluation of retina and optic nerve head in cats with mild intraocular pressure elevation using optical coherence tomography. These abstracts provide valuable insights into the field of veterinary ophthalmology and can be useful for researchers and practitioners in this area. [Extracted from the article]

A 12‐year‐old neutered male Chihuahua dog was diagnosed with pituitary‐dependent hypercortisolism and treated with trilostane. Eighty‐nine days later, the dog showed lethargy accompanied by hyponatraemia and hyperkalaemia. Hypoadrenocorticism due to trilostane was suspected, but the result of the adrenocorticotropic hormone stimulation test was not conclusive. Contrast‐enhanced ultrasound showed loss of adrenocortical blood flow in both adrenal glands, indicating adrenocortical hypoperfusion and isolated hypoadrenocorticism. Treatment with fludrocortisone acetate improved the condition and electrolyte abnormalities. Thirteen months later, the dog showed alopecia, and an adrenocorticotropic hormone stimulation test revealed increased cortisol concentration, indicating hypercortisolism recurrence. The dog died due to progressive deterioration 22 months after the initial presentation. Post‐mortem examination revealed focally extensive necrosis with marked calcification in the parenchyma of the adrenal glands and regeneration of the cells in the zona fasciculata with severe fibrosis. Adrenocortical hypoperfusion detected by contrast‐enhanced ultrasound can support the diagnosis of adrenal necrosis and hypoadrenocorticism. [ABSTRACT FROM AUTHOR]

The aging process is still not fully understood, although it has been studied for centuries. One of the processes in the brain during aging is the accumulation of extracellular and intracellular deposits of amyloid and lipofuscin. Deposits of various polyglucosan bodies (PGBs) are also found in brain tissue. The accumulation of the Lafora bodies (LB), a type of PGBs, can cause the Lafora disease (LD). Initial signs of the disease in humans are tonic-clonic seizures with blindness and myoclonus seizures. Normally, all haematological and biochemical indices are within the reference range in dogs with this disease. In this case, a 7-year-old Chihuahua dog with tonic-clonic seizures was presented. According to history, neurological examination, and blood test, toxic, metabolic, and infectious causes for the seizures were ruled out. The dog was started on phenobarbital 2.5 mg/kg twice daily per os. Two years later, the dog died due to complications caused by a duodenal foreign body. Postmortem examination revealed hyperaemic meninges and an enlarged, oedematous brain with flattened gyri and narrowed sulci. Histopathological examination revealed multifocal to diffuse, randomly distributed PGBs that were positive on periodic acid-Schiff (PAS) staining. The diagnosis of LD in dogs is of great importance because they are a good experimental model for neurological studies of neurodegenerative diseases in humans. [ABSTRACT FROM AUTHOR]

In this study we undertook a comprehensive analysis of a Pet Tumour Registry of the Canary Archipelago (PTR‐CA) in Spain to investigate the epidemiology of canine cutaneous round cell tumours. From a database of 2526 tumours collected from 2003 to 2020, we conducted a longitudinal analysis of the main trends in diagnosis, age, multiplicity and anatomical distribution as well as a case–control study comparing these cases with the contemporaneous canine population of the Canary Archipelago to analyse breed distribution. In line with former studies, we found histiocytomas mostly affect young dogs (2, IQR 1–5) and mast cell tumours affect middle‐to‐old dogs (8, IQR 6–10) with grade 1 affecting at younger ages (6.5, IQR 6–8) than both grade 2 (8, IQR 6–10 years) and grade 3 (9, IQR 7–11). Histiocytomas and plasmacytomas showed a similar anatomical distribution appearing mainly on the face, head and neck regions while mast cell tumours occur mainly on limbs and trunk. Higher risk for mast cell tumours and histiocytomas were found for Bulldog‐related breeds such as Boxer (ORMCT = 23.61, CI95%: 19.12–29.15, ORHCT = 10.17, CI95%: 6.60–15.67), Boston Terrier (ORMCT 19.47, CI95%: 7.73–49.05, ORHCT 32.61, CI95%: 11.81–90.07) and Pug (ORMCT 8.10, CI95%: 5.92–11.07, ORHCT 7.87, CI95%: 4.66–13.28) while Chihuahua dogs showed significantly less risk (ORMCT 0.18, CI95%: 0.09–0.33, ORHCT 0.41, CI95%: 0.21–0.78). Notably, the Canarian Mastiff, a local breed, had a low risk of suffering from a mast cell tumour which raises the question of whether this relates to a genetic peculiarity of this breed or some husbandry and environmental factor. [ABSTRACT FROM AUTHOR]

This report describes a dog diagnosed with insertional biceps tendinopathy that was palliated with intra‐articular triamcinolone acetonide injections. The patient was a 6‐year‐old spayed female Chihuahua dog that had left thoracic limb lameness for 3 months before presentation. On physical examination, moderate pain was elicited by performing the biceps test and isolated full elbow extension on the left thoracic limb. Gait analysis showed asymmetrical peak vertical force and vertical impulse between thoracic limbs. Computed tomography (CT) revealed enthesophyte formation on the ulnar tuberosity of the left elbow joint. Ultrasonography showed a heterogeneous fibre pattern at the biceps tendon insertion site on the left elbow joint. These findings confirmed insertional biceps tendinopathy based on physical examination, CT and ultrasonography results. The dog received an intra‐articular triamcinolone acetonide injection with hyaluronic acid in the left elbow joint. Clinical signs improved after the first injection, including a range of motion, pain and gait. A second injection was given in the same manner because of recurring mild lameness 3 months later. No clinical signs were observed during the follow‐up period. [ABSTRACT FROM AUTHOR]

A 4-year-old Chihuahua dog was referred for bilateral corneal ulcers. Slightly raised white fluorescein-positive plaque-like corneal lesions in both eyes appeared as intense hyperreflective areas with posterior shadowing on optical coherence tomography (OCT). Based on corneal cytology and culture, Candida albicans-induced fungal keratitis was diagnosed. Despite treatment, on OCT, endothelial plaques, increased stromal infiltration thickness, vertical shapes of the ulcer edge, and necrotic stromal space were judged to be aggravation of the disease, and surgery was performed. Conjunctival grafting surgery with topical 1% voriconazole effectively resolved fungal keratitis. OCT can provide detailed and objective information related to the disease prognosis. [ABSTRACT FROM AUTHOR]

Chihuahuas are one of the most common small breed dogs in Japan, and this breed is known to be predisposed to myxomatous mitral valve disease (MMVD). Echocardiographic assessment is essential for definitive diagnosis of MMVD in dogs as well as determining the stage. Because the Chihuahua's body size is the smallest among the dog breeds and the widely used echocardiographic reference range is established on the basis of larger dogs, it is unclear whether the existing reference range can be applied to the Chihuahua breed as well. Therefore, this study aimed to determine an echocardiographic reference range for Chihuahua dogs. The left atrial short-axis diameter (LA), aortic valve short-axis diameter, interventricular septum thickness at enddiastole, left ventricular internal dimension at end-diastole (LVIDd), and left ventricular posterior wall thickness at end-diastole from 47 healthy Chihuahuas were analyzed. These parameters increased logarithmically as body weight increased. Furthermore, LA and LVIDd were within the previously established reference range generated primarily from multiple breeds of moderate to large breed dogs. [ABSTRACT FROM AUTHOR]

Simple Summary: Neuronal ceroid lipofuscinosis (NCL) is a rare group of lethal neurodegenerative lysosomal storage diseases, in which a homozygous single base-pair deletion (c.846delT) in the canine CLN7/MFSD8 gene has been identified as a causative mutation in Chihuahuas. In this study, we aimed to determine the carrier rate of NCL in Chihuahuas in Japan based on the screening of puppies using a newly designed real-time PCR assay. A survey conducted among 1007 Chihuahua puppies indicated that the carrier rate was 1.29%. Given the lethality of this disease, the mutant allele frequency (0.00645) is sufficiently high to warrant measures for disease control and prevention using the genotyping assay. Neuronal ceroid lipofuscinosis (NCL) is a group of rare lethal neurodegenerative lysosomal storage diseases that occur in a range of dog breeds, including Chihuahuas. Recently, a homozygous single base-pair deletion (c.846delT), which causes a frame shift generating a premature stop codon (p.Phe282Leufs13*) in the canine CLN7/MFSD8 gene, has been identified as a causative mutation for NCL in Chihuahuas. The objective of this study was to determine the frequency of the mutant allele and/or carrier rate of NCL in Chihuahuas in Japan using a newly designed real-time PCR assay. Samples of saliva were randomly collected from 1007 Chihuahua puppies during physical examinations prior to the transportation to pet shops. Screening results revealed a carrier rate of 1.29%, indicating a mutant allele frequency (0.00645) that is considered sufficiently high to warrant measures for the control and prevention of this lethal disease. The genotyping assay designed in this study could make a valuable contribution to the control and prevention of NCL. [ABSTRACT FROM AUTHOR]

A Chihuahua dog showed persistent itching in the right ear canal. Anti-inflammatory medicines and prednisolone were ineffective and total ear canal ablation was performed. Histological diagnosis was chronic otitis externa. Eosinophilic intranuclear inclusion bodies (Cowdry type A and full-type) were occasionally observed in the ceruminous gland epithelium. The inclusion bodies were negative for nucleic acid and ultrastructurally composed of fibrous structures (approximately 10 nm in width). Viral infection was initially suspected, but polymelase chain reaction tests did not detect the expected viral genes. Immunohistochemistry revealed that the inclusion bodies were positive for heat shock protein 70 (HSP70), suggesting that these bodies could be protein aggregates including HSP70. The etiology of this lesion has not been elucidated, but chronic inflammation may influence the cytoplasm-to-nuclear transportation of HSP70. To the best of our knowledge, this is the first report of canine chronic otitis externa with HSP70-positive intranuclear inclusion bodies. [ABSTRACT FROM AUTHOR]

Pravastatin (PS) has been found to increase left ventricle (LV) expansion capacity and decrease LV constriction and left atrial pressure in healthy dogs. To date, there are no available reports on the effects of PS in dogs with hypercholesterolemia with chronic heart failure (CHF). This case report demonstrates a successful long-term treatment plan using PS in a dog suffering from mitral insufficiency with hyperlipidemia. A 12-year-old, castrated male Chihuahua dog had mitral insufficiency with hyperlipidemia. The dog presented with symptoms of chronic coughing. PS was orally administered (1 mg/kg, SID) in addition to general treatment for mitral insufficiency. The follow-up period was 375 days. PS administration decreased the heart rate (HR), vertebral heart size (VHS), and N-terminal probrain natriuretic peptide (NT-proBNP) concentration of the dog. In addition, PS administration also improved chronic cardiac failure induced by mitral insufficiency and hyperlipidemia. This report suggests that PS can be useful as an adjunctive therapeutic for dogs with hypercholesterolemia with mitral insufficiency. [ABSTRACT FROM AUTHOR]

Background: The Chihuahua dog breed is known for frequent occurrence of a bregmatic fontanelle on the dorsal skull. A common conception is that this skull defect is a clinically irrelevant finding. No studies, however, describe its prevalence or whether it is accompanied by other persistent fontanelles (PFs). Although Chihuahuas are predisposed to Chiari‐like malformation (CM) and syringomyelia (SM), it is unknown whether PFs occur more commonly in dogs with clinical signs that are caused by CM or SM. Hypothesis/Objectives: To describe the number and location of PFs at cranial sutures (CSs) and to compare the occurrence of these PFs in dogs with and without CM/SM‐related clinical signs. We hypothesized that PFs also occur commonly at lateral and caudal cranial surfaces, affect a higher number of CSs, and are larger in dogs with CM/SM‐related clinical signs. Animals: Fifty client‐owned Chihuahuas with or without CM/SM‐related clinical signs. Results: Of the 50 dogs evaluated, 46 (92%) had either 1 or several PFs. The mean ± SD number of PFs was 2.8 ± 3.0 (range, 0‐13). A total of 138 PFs occupied 118 CSs with 57 (48%) located dorsally, 44 (37%) caudally, and 17 (14%) laterally. The number of CSs affected by PFs was significantly higher (P ≤.001) and total PF area was significantly larger (P =.003) in dogs with CM/SM‐related clinical signs. Conclusions and Clinical Importance: Persistent fontanelles are very common in this group of Chihuahuas and appear at dorsal, lateral, and caudal cranial surfaces. They are more numerous and larger in Chihuahuas with CM/SM‐related clinical signs. [ABSTRACT FROM AUTHOR]

Extensive exophytic pigmented viral plaques developed on a Chihuahua dog causing pruritus and discomfort. Neither the medical treatments used nor a papillomavirus vaccine resulted in clinical improvement. Laser surgery removed some plaques, yet others developed. This case illustrates the difficulty in treating viral plaques and the progressive nature of this disease. [ABSTRACT FROM AUTHOR]

A 10-year-old intact male Chihuahua dog was presented with a history of exercise intolerance, coughing with a gag, panting and syncope. Heart auscultation revealed the dog was having left apical systolic murmur grade IV/VI with radiographic findings of cardiomegaly, pulmonary oedema and bronchial collapse. Echocardiography confirmed the dog had degenerative mitral valve disease (DMVD) with echocardiographic findings of thickened mitral valve leaflets and severe mitral regurgitation. The dog was treated with angiotensin converting enzyme inhibitor (ACEI), diuretics and bronchodilator. The dog responded well to the treatment with no occurrence of syncope since the last episode and reduced in frequency of cough. Pimobendan was added on to the treatment six months later as the dog started to have productive cough. Improvement was seen after 2 weeks where episodes of productive cough were greatly reduced with improved appetite. The prognosis is fair to poor in this case due to signs of congestive heart failure (Stage C) that required a life-long treatment therapy. [ABSTRACT FROM AUTHOR]

Background: In the dog, the correct management of parturition and the prompt neonatal evaluation and assistance can reduce the perinatal mortality rates that are particularly high in toy breeds. Newborn evaluation and factors addressing prognosis are pivotal to guarantee the correct neonatal assistance. Assessment of the Apgar score with viability classification and birthweight are recognized as predictors for neonatal survival in dogs, but breed-specific data are needed for a more feasible application in the dog species, in which wide differences among breeds are known. The present study aimed therefore to: (a) assess the role of Apgar score and birthweight as predictors for the survival of Chihuahua newborn puppies in the first 24 h of life; (b) to assess a cut-off of the Apgar score and birthweight values that can predict the survival of Chihuahua newborn puppies in the first 24 h after birth; (c) to assess the possible effect played by maternal parity, newborn gender and litter-size on Apgar score in Chihuahua newborn puppies, in order to provide breed-specific data for a better neonatal assistance. Results: Data obtained from 176 normal developed Chihuahua puppies born by elective Caesarean section, showed that 62%, 28% and 10% of puppies were classified in the Apgar score classes 7–10, 4–6 and 0–3, respectively, with survival at 24 h after birth of 97%, 96%, 39%, in the three Apgar classes of viability, respectively. Apgar score was a better predictor for survival at 24 h after birth than birthweight (AUC 0.93, P < 0.0001; AUC 0.69, P < 0.01, respectively). Litter-size of 7 puppies/litter plays a negative effect on Apgar score. Apgar score is a better predictor of survival at 24 h than birthweight, and the best cut-off of Apgar score for survival at 24 h after birth is 4, with 96% sensitivity and 77% specificity. Conclusions: The different proportion of "normal viable" and "less viable" neonates in comparison to other studies highlights that Chihuahua puppies born by elective Caesarean section should be carefully evaluated at birth to provide correct assistance. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 4-year-old 6.2-kg castrated male terrier-Poodle mixed-breed dog was evaluated because of a 6-month history of bruxism. It mentions oral cavity examination performed when the dog was sedated did not identify the cause of the bruxism and neurologic examination revealed bright mentation with hyperreactivity to stimuli around the face. It also mentions diagnoses for the bruxism included a lesion associated with the oral cavity.

Copyright of Compendium of Veterinary Sciences / Compendio de Ciencias Veterinarias is the property of Facultad de Ciencias Veterinarias de la Universidad Nacional de Asuncion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study was to assess the accuracy of surgeons' perception in determining the efficacy of spinal decompression compared to postoperative magnetic resonance imaging (MRI) findings in a population of dogs with IVD extrusion; to evaluate whether postoperative MRI findings had a better association with outcome or recovery time as compared to surgeons' evaluation; to investigate the relationship of MRI intramedullary changes with outcome and recovery time. None of the dog owners reported significant changes in the behavior of their dog during the given period, and despite the ventricular enlargement the dogs were able to perform the trained task fulfilling above mentioned strict criteria. The study was carried on 19 Border collies divided into two groups: A; dogs with confirmed IE (n=10) and B; dogs with no history of seizures and normal brain MRI (n=9). Three dogs suffered SE, 6 dogs had clusters and 3 dogs isolated seizures. Of dogs with suspected encephalitis, 12/13 dogs had multifocal MRI lesions. [Extracted from the article]

A personal narrative is presented in which author share her experience of bringing Chihuahua Dexter, toy dog from Boston, Massachusetts to Jonesboro, Arkansas.

An 11-year-old castrated male Chihuahua dog was presented with complaints of polyuria, polydipsia, abdominal enlargement, and alopecia. Hyperadrenocorticism was diagnosed on the basis of clinical signs, blood tests, adrenocorticotropin-stimulation test results, and an elevated serum adrenocorticotropin concentration. Contrast-enhanced magnetic resonance imaging showed that the pituitary gland was enlarged, compatible with a pituitary macroadenoma. Pituitary-dependent hyperadrenocorticism was suspected, and transsphenoidal hypophysectomy was thus performed for complete resection of the tumor. After surgery, the serum adrenocorticotropin concentration normalized and the hyperadrenocorticism resolved. Histological and immunocytochemical analyses revealed a benign tumor composed of mature neuronal cells and glial cells, suggestive of a ganglioglioma with immunolabeling for adrenocorticotropin. Careful analysis of the resected tumor revealed no pituitary adenoma tissue. The clinical and histopathologic findings indicated that the ganglioglioma was directly responsible for the hyperadrenocorticism. This is the first case of hyperadrenocorticism caused by a ganglioglioma in a dog. [ABSTRACT FROM AUTHOR]

In 2007, the United States successfully eliminated canine rabies virus variant. Globally, however, dogs remain the principal source of human rabies infections. Since 2007, three cases of canine rabies virus variant were reported in dogs imported into the United States, one each from India (2007), Iraq (2008), and Egypt (2015) (1-3). On December 20, 2017, a dog imported into the United States from Egypt was identified with rabies, representing the second case from Egypt in 3 years. An Egyptian-based animal rescue organization delivered four dogs from Cairo, Egypt, to a flight parent (a person solicited through social media, often not affiliated with the rescue organization, and usually compensated with an airline ticket), who transported the dogs to the United States. The flight parent arrived at John F. Kennedy International Airport (JFK) in New York City and, via transporters (persons who shuttle dogs from one state to another), transferred the dogs to foster families; the dogs ultimately were adopted in three states. The Connecticut Department of Public Health Laboratory (CDPHL) confirmed the presence of a canine rabies virus variant in one of the dogs, a male aged 6 months that was adopted by a Connecticut family. An investigation revealed the possibility of falsified rabies vaccination documentation presented on entry at JFK, allowing the unvaccinated dog entry to the United States. This report highlights the continuing risk posed by the importation of dogs inadequately vaccinated against rabies from high-risk countries and the difficulties in verifying any imported dog's health status and rabies vaccination history. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 4-year-old spayed female Chihuahua suffering from the acute epileptic seizures admitted to the Ian Animal Diagnostic Imaging Center for Magnetic resonance imaging (MRI) of the brain with the anesthesia. It notes that the hydrocephalus was the reason for the seizure in the dog. The article discusses the impact of the anesthesia on the epileptic seizures.

This report describes a case of severe lactic acidosis associated with a suspected succinic semialdehyde dehydrogenase (SSADH) deficiency in a 5-month-old Chihuahua. The dog was presented for obtundation and "drunk-like" behavior of 1 month duration. Venous blood gas analysis revealed a severe lactic acidosis (blood pH 6.938; reference interval 7.35-7.45; lactate concentration 18.27 mmol/L; reference interval 0.8-2.0 mmol/L). As other causes of encephalopathy and hyperlactatemia were ruled out, an inborn error of lactate metabolism was suspected. Quantitative organic acid analysis showed marked elevations of urine lactic acid, pyruvic acid and gamma-hydroxybutyric acid (or 4-hydroxybutyric acid) concentrations. Activity level of SSADH, measured in the dog's cultured lymphoblasts, was 30% of that recorded in three healthy dogs, suggesting SSADH deficiency. The dog initially responded to treatment, but eventually deteriorated, and was euthanized. Organic acidurias are being increasingly recognized in veterinary medicine; however SSADH deficiency has never been reported in dogs. Early identification of inherited organic aciduria in domestic animals might facilitate prompt, appropriate treatment, and potentially facilitate modelling of corresponding human pathologies. [ABSTRACT FROM AUTHOR]

A case study of a Chihuahua suffering from syncope and bradycardia is offered. It mentions that there was lack of evidence for its medical history as the dog was rescued from a house. The dog displayed signs of lethargy and was diagnosed with left-sided congestive heart failure and bradycardia. The finding of echocardiography that stated the absence of P waves is presented. The dog's treatment with pacemaker and administration of medications such as furosemide is presented.

The article presents a case study of a 10-year-old 5.3-kg (11.7-lb) neutered male Chihuahua with mediastinal mass and pleural effusion. The Chihuahua underwent physical examination, thoracic radiography, and contrast-enhanced computed tomography (CT) of the thorax resulting to the diagnosis of cranial vena cava aneurysm. The dog was treated with diltiazem, digoxin, and clopidogrel.

Patellar luxation is one of the more common orthopaedic diseases of dogs and is relatively frequent in some toy breeds, including the Chihuahua and Bichon Frise. Using data provided by the Swedish Kennel Club, genetic parameters, including heritability, were estimated for patellar luxation in the Chihuahua from 1999 to 2014 and in the Bichon Frise from 1997 to 2014. The effects of the current screening programmes for patellar luxation in these breeds were evaluated. Patellar luxation was defined as a binary trait, treating dogs as affected or unaffected. The edited data included 7024 records for the Chihuahua and 1071 records for the Bichon Frise. Patellar luxation was analysed using mixed linear and threshold animal models, including fixed effects of sex, birth month, birth year, age at veterinary examination, random effects of the examining veterinary surgeon, genetic effect of the individual and residual. The prevalence of patellar luxation was 23% in the Chihuahua and 12% in the Bichon Frise. Using threshold analysis, estimated heritabilities were 0.25 for the Chihuahua and 0.21 for the Bichon Frise on the observable scale, and 0.46 for the Chihuahua on the underlying scale. It was concluded that there is genetic variation in patellar luxation and that there has been a slight genetic improvement over the study period in the Chihuahua. Further genetic progress would be facilitated by selection using estimated breeding values based on veterinary screening records. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To describe a serious adverse event as a result of rapid intravenous injection of undiluted levetiracetam in a dog. Case Summary: An 8‐year‐old female spayed Chihuahua was evaluated for cluster seizures and tachypnea. The patient was administered an intravenous dose of undiluted levetiracetam (60 mg/kg) and immediately developed tachycardia, hyperglycemia, hypotension, and a dull mentation. The patient's blood pressure and mentation did not respond to intravenous fluid boluses but improved immediately after administration of epinephrine intravenously. The patient subsequently developed respiratory failure necessitating mechanical ventilation, prior to cardiac arrest. Necropsy examination noted a pulmonary inflammatory cell infiltrate, pulmonary edema, and interstitial pneumonia. New or Unique Information Provided: This report documents a serious adverse event associated with intravenous levetiracetam administration to a dog. [ABSTRACT FROM AUTHOR]

Background Chiari-like malformation ( CM) and syringomyelia ( SM) are widely reported in Cavalier King Charles Spaniels and Griffon Bruxellois dogs. Increasing evidence indicates that CM and SM also occur in other small and toy breed dogs, such as Chihuahuas. Objectives To describe the presence of SM and craniocervical junction ( CCJ) abnormalities in Chihuahuas and to evaluate the possible association of CCJ abnormalities with SM. To describe CM/ SM-related clinical signs and neurologic deficits and to investigate the association of CM/ SM-related clinical signs with signalment, SM, or CCJ abnormalities. Animals Fifty-three client-owned Chihuahuas. Methods Prospective study. Questionnaire analyses and physical and neurologic examinations were obtained before magnetic resonance and computed tomography imaging. Images were evaluated for the presence of SM, CM, and atlantooccipital overlapping. Additionally, medullary kinking, dorsal spinal cord compression, and their sum indices were calculated. Results Scratching was the most common CM/ SM-related clinical sign and decreased postural reaction the most common neurologic deficit in 73 and 87% of dogs, respectively. Chiari-like malformation and SM were present in 100 and 38% of dogs, respectively. Syringomyelia was associated with the presence of CM/ SM-related clinical signs ( P = 0.034), and medullary kinking and sum indices were higher in dogs with clinical signs ( P = 0.016 and P = 0.007, respectively). Conclusions and Clinical Importance Syringomyelia and CCJ abnormalities are prevalent in Chihuahuas. Syringomyelia was an important factor for the presence of CM/ SM-related clinical signs, but many dogs suffered from similar clinical signs without being affected by SM, highlighting the clinical importance of CCJ abnormalities in Chihuahuas. [ABSTRACT FROM AUTHOR]

A 9-year-old, spayed female Chihuahua was presented with a 1-week history of lethargy and anorexia. Abdominal ultrasonography and computed tomography found bilateral adrenal masses without metastasis. Serum cortisol levels that were sampled before and after an adrenocorticotropic hormone stimulation test were within reference ranges. Lethargy and anorexia completely resolved after short-term fluid therapy; the clinical signs did not occur for approximately 8 months until her sudden death. A postmortem examination revealed bilateral adrenocortical carcinomas and liver metastasis. Primary adrenocortical carcinomas developed in the dog met the definition of bilateral incidental adrenal gland masses (IAGMs). This is the first case report to demonstrate based on histological identification that adrenocortical carcinomas cause bilateral IAGMs in dogs. [ABSTRACT FROM AUTHOR]

A novel form of neuroaxonal dystrophy is described in 3 Chihuahua pups, 2 of which were from the same litter. It was characterized not only by accumulation of numerous and widely distributed axonal swellings (spheroids) but also by a severe cavitating leukoencephalopathy. The dogs presented with progressive neurological signs, including gait abnormalities and postural reaction deficits. Magnetic resonance images and gross examination at necropsy revealed dilation of lateral ventricles and cerebral atrophy, accompanied by cavitation of the subcortical white matter. Histopathologically, severe axonal degeneration with formation of large spheroids was found in the cerebral and cerebellar white matter, thalamus, and brainstem nuclei. Small-caliber spheroids were observed in the cerebral and cerebellar gray matter. The telencephalic white matter had severe myelin loss and cavitation with relative sparing of the U-fibers. Different from previously reported cases of canine neuroaxonal dystrophy, in these Chihuahuas the spheroid distribution predominantly involved the white matter with secondary severe leukoencephalopathy. [ABSTRACT FROM AUTHOR]

Here, we explored the rate of telomere attrition with increasing age by real-time quantitative PCR (qPCR) in a short-(Chihuahua dog) and long-(Asian elephant) lived species. A total of 122 Asian elephants (female = 106, male = 16) ranging from 24-840 months of age, and 89 Chihuahuas (female = 65, male = 24) 1-179 months of age were used in this study. We found that young (pre- and peri-pubertal) Asian elephants had a higher relative telomere length (RTL) compared to dogs. A low, but significant negative relationship between RTL and increasing age was observed in both Chihuahuas (R2=0.0490, P=0.0017) and Asian elephants (R2=0.0177, P=0.0210). The estimated rate of telomere loss for males and females of both species ranged from -0.0023 to -0.0065, with no clear differences between gender or species. Results suggest that Asian elephants may start with longer telomeres than Chihuahuas, as RTL was higher, but then the rate of telomere attrition proceeds at a similar rate in both species. Age accounted for only a small percentage of the variation in RTL in both Chihuahua dogs and Asian elephants, however. Thus, its use as a biological tool for age estimation would appear to be limited for these species. [ABSTRACT FROM AUTHOR]

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The neuronal ceroid lipofuscinoses (NCLs) are hereditary neurodegenerative disorders characterized by progressive declines in neurological functions, seizures, and premature death. NCLs result from mutations in at least 13 different genes. Canine versions of the NCLs can serve as important models in developing effective therapeutic interventions for these diseases. NCLs have been described in a number of dog breeds, including Chihuahuas. Studies were undertaken to further characterize the pathology of Chihuahua NCL and to verify its molecular genetic basis. Four unrelated client owned Chihuahuas from Japan, Italy and England that exhibited progressive neurological signs consistent with a diagnosis of NCL underwent neurological examinations. Brain and in some cases also retinal and heart tissues were examined postmortem for the presence of lysosomal storage bodies characteristic of NCL. The affected dogs exhibited massive accumulation of autofluorescent lysosomal storage bodies in the brain, retina and heart accompanied by brain atrophy and retinal degeneration. The dogs were screened for known canine NCL mutations previously reported in a variety of dog breeds. All 4 dogs were homozygous for the MFSD8 single base pair deletion ( MFSD8 : c.843delT ) previously associated with NCL in a Chinese Crested dog and in 2 affected littermate Chihuahuas from Scotland. The dogs were all homozygous for the normal alleles at the other genetic loci known to cause different forms of canine NCL. The MFSD8 : c.843delT mutation was not present in 57 Chihuahuas that were either clinically normal or suffered from unrelated diseases or in 1761 unaffected dogs representing 186 other breeds. Based on these data it is almost certain that the MFSD8 : c.843delT mutation is the cause of NCL in Chihuahuas. Because the disorder occurred in widely separated geographic locations or in unrelated dogs from the same country, it is likely that the mutant allele is widespread among Chihuahuas. Genetic testing for this mutation in other Chihuahuas is therefore likely to identify intact dogs with the mutant allele that could be used to establish a research colony that could be used to test potential therapeutic interventions for the corresponding human disease. [ABSTRACT FROM AUTHOR]